The present invention relates generally to brakes of the type having a hollow cylindrical braking member and a caliper member endwise straddling the braking member.
Such a brake usually comprises a fixed support which is adapted to be secured to some sort of supporting member, e.g. the stub axle of a wheel to be braked, the hollow cylindrical rotary braking member, known in France as the "crown, " which is adapted to be keyed for rotation with the shaft to be braked, i.e. the axle of the wheel, two brakes shoes, respectively disposed on opposite sides of the cylindrical braking member and actuating means adapted to act on said brake shoes for urging them against the braking member in a generally radial direction relative to the cylindrical braking member, referred to as the gripping axis, extending through the central zones of the brake shoes.
The present invention relates more particularly to the use of a generally C-shaped caliper member which is shiftably mounted for radial movement relative to the braking member and straddles the actuating means, the brake shoes and the caliper member and which comprises a first limb associating it which the actuating means for actuating a first brake shoe and a second limb by which it acts against a second brake shoe for transmitting to it the force applied by the actuating means.
More often, the actuating means are embodied in the caliper or transfer member which thenceforth comprise an actuating member, the actuating means comprising a piston displaceable inside a cylinder in the corresponding limb of the caliper member. Still, it may even be a part independent of the actuating means comprising, for example, two pistons, one acting against a first brake shoe and the other against a corresponding limb of the caliper member.
In either event one of the difficulties to be overcome in the construction of brakes of this type results from the need to insure suitable axial retention of the caliper member while permitting easy access to the brake shoe with a view to their replacement when necessary.
Usually the axial retention of the caliper member is effected by means of a retaining bar which extends substantially perpendicular to an axial plane of the brake containing the gripping axis, the retaining bar having an intermediate portion against which the intermediate portion of the caliper member bears axially and two side branches adapted to permit securement to the fixed support.
Most frequently the securement is effected by means of screws, the retaining bar having at the ends of its side branches, turnover portions with holes for receiving the screws.
Although this arrangement has given and continues to give satisfaction, it has various drawbacks.
First, it is a rather expensive arrangement since it employs screws requiring the tapping of holes in the fixed support for threaded arrangement with the screws.
Further, it is not an entirely reliable arrangement inasmuch as such screws may work loose in use due to vibrations to which brakes are inevitably subjected, absent special means for preventing the unloosening of the screws which further augments the cost of the assembly.
Finally, for access to the brake shoes of such an arrangement the screws effecting the axial retention of the caliper member must be removed, which as an operation, although easy in itself, is not always simple to carry out and may be very time-consuming.